In the manufacture of an automobile body, plural pieces of steel plate are welded together to form a blank that is well tailored for a subsequent processing operation, such as press-forming. The blank is generally called “tailor-welded blank” or “tailored blank”. By using the tailored blank process, it is possible to weld together a variety of materials of different thickness, tensile strength and so on.
In one application shown in Japanese Patent Laid-open Publication (JP-A) No. 2003-19979, a tailored blank is used to form a dashboard lower panel of a vehicle body structure. The dashboard lower panel 101, as shown in FIG. 9A hereof, is a partition wall separating a passenger room 102 and an engine room 103. The dashboard lower panel 101 is formed from a tailored blank consisting of a thick metal plate 104 and a thin metal plate 106 joined at one end 105, 107 by mash-seam welding. The dashboard lower panel (i.e., tailored blank article) 101 has an opening 116 formed therein for introducing a vehicle part from the engine room side into the passenger room side. The opening 116 extends over the thick and thin metal plates 104, 106 across a welded portion 108.
As shown in FIG. 9B, the dashboard lower panel 101 has an outer surface 103 facing the engine room 103 (FIG. 9A), and an end flange 112 of a front side frame is attached to the outer surface 103. Similarly, an insulator panel 113 is attached to an inner surface 109 of the dashboard lower panel 101. The inner and outer surfaces 109, 111 of the dashboard lower panel 101 are coated with paint film layers 114, 114.
FIG. 9C is a cross-sectional view taken along line IXC—IXC of FIG. 9A. As shown in this figure, a cup-shaped lead-in member 118 is attached to the outer surface 111 of the dashboard lower panel 101 with a seal 117 disposed therebetween so as to cover the opening 116 from the engine room side. The cup-shaped lead-in member 118 and the opening 116 together form an opening structure 115.
The dashboard lower panel 101 having such opening structure 115 has a problem that when the engine room 103 is washed by means of water, water may leak into the passenger room side from a mating surface between the seal 117 and a step formed along the welded portion 108 of the dashboard lower panel 101.